This paper presents updated estimates of source parameters for GW150914 , a binary black-hole coalescence event detected by the Laser Interferometer Gravitational-wave Observatory ( LIGO ) on September 14 , 2015 [ ] .
Reference [ ] presented parameter estimation of the source using a 13-dimensional , phenomenological precessing-spin model ( precessing IMRPhenom ) and a 11-dimensional nonprecessing effective-one-body ( EOB ) model calibrated to numerical-relativity simulations , which forces spin alignment ( nonprecessing EOBNR ) .
Here we present new results that include a 15-dimensional precessing-spin waveform model ( precessing EOBNR ) developed within the EOB formalism .
We find good agreement with the parameters estimated previously [ ] , and we quote updated component masses of 35 ^ { +5 } _ { -3 } \mathrm { M } _ { \odot } and 30 ^ { +3 } _ { -4 } \mathrm { M } _ { \odot } ( where errors correspond to 90 % symmetric credible intervals ) .
We also present slightly tighter constraints on the dimensionless spin magnitudes of the two black holes , with a primary spin estimate < 0.65 and a secondary spin estimate < 0.75 at 90 % probability .
Reference [ ] estimated the systematic parameter-extraction errors due to waveform-model uncertainty by combining the posterior probability densities of precessing IMRPhenom and nonprecessing EOBNR .
Here we find that the two precessing-spin models are in closer agreement , suggesting that these systematic errors are smaller than previously quoted .